Before settling on a particular air purifier model, there are several things you have to take into account. And by this, we mean more than looking at how many filters the device comes with, how much noise it generates, and whether it looks nice on your floor, table, or hanging on a wall. Yes, we’re talking about the size of an air purifier.
Common Ways of Sizing an Air Purifier
There are three ways you can determine whether an air purifier is right for your room, rooms, or home—namely, the square-foot method, the cubic-foot method, and the CADR method.
Square-Foot Method
The square-foot method is arguably the easiest way to size an air purifier. All you really need to know is how far an air purifier can reach and whether the square footage of a room is equal to or less than the air purifier’s reach.
To use this method, you first have to determine which room or rooms you want your air purifier to purify. The wider the area and the more rooms you include, the larger the air purifier you’ll need.
For instance, if you want to purify the air in a bedroom, make sure you find an air purifier that can cover at least the square footage of your bedroom. If you want an air purifier for your entire apartment, add the dimensions of every room together to come up with the total square footage, and then look for an air purifier that can cover at least that much space.
Here’s an easier way to look at it:
Air Purifier’s Reach (in square feet) ≥ the L X W of a room or all rooms in total.
For instance, the air purifier’s maximum reach should be at least 80 square feet if you want to purify an 8 x 10-foot bedroom. If you want an air purifier for your kitchen (160 square feet) and living room (320 square feet), it should have a maximum reach of at least 480 square feet (160 + 320).
Please note that there are entire-home air purifiers available, as well. In fact, users claim that entire-home air purifiers—i.e., air purifiers that can cover an entire home—is more power-efficient than getting multiple short-range air purifiers. This is just something you should keep in mind.
Cubic-Foot Method
Since we live in a 3D world, how is it that an air purifier’s square-foot rating can be used to determine whether an air purifier is right for a particular room? Well, to be completely honest, it can’t.
If you wish to find the most suitable air purifier for a particular room, you’ll have to look at the device’s CFM (cubic feet per minute) rating. CFM denotes how much air the device suctions in every 60 seconds, so a higher CFM rating will mean quicker air purification at the cost of increased energy consumption.
In addition, you’ll have to take into consideration how many times you want your air purifier to clean the air in a room. This is known as the air-change-per-hour (ACH) figure. A higher ACH means you want your air purifier to clean the air more times per hour.
So, here’s how you can use the air purifier’s CFM to size a room:
- Calculate the L X W X H of a room or rooms
- Determine the air ACH rate
- Ideal CFM rating = (L X W X H) X ACH
For instance, the perfect air purifier for an 8 x 10 x 12-cubic-foot bedroom that produces at least 2 ACH is 1,920 CFM ((8 x 10 x 12) x 2).
CADR Method
Last up, we have the CADR method. CADR stands for clean air delivery rate, which is a CFM score that denotes how efficient an air purifier is at removing smoke, pollen, and dander particles from the air. For instance, some of the best air purifiers for bedrooms have CADR scores of at least 100 CFM across the board.
Using the CADR method is a lot more straightforward than the other air-purifier-sizing methods. To do this, you just have to remember the 2/3 rule, which means that the CADR scores of an air purifier should be at least two-thirds of a room’s total area.
So, to illustrate this idea, let’s assume that you want an air purifier for your 8 x 10-square-foot bedroom. The ideal CADR rating for your air purifier should be 2/3 x 80 = 53 CFM, which isn’t very difficult to find.
However, you have to remember that air purifier manufacturers aren’t obligated to put their air purifiers under rigorous CADR tests. This means that using this air-purifier-sizing method may not be applicable in all air purifiers since many of them don’t have CADR scores.
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